For spiritual research matter has sprung from Spirit, is nothing but densified Spirit.
As a comparison, picture a vessel with water in it. Think of one part of the water being cooled down until it turns to ice. Now what is the ice? It is water, water in another form, in a solid condition. This is the way that spiritual research looks at matter. As water is related to ice so is Spirit to matter. As ice is no more than a result of water, so is matter nothing else than a result of Spirit, and as ice can become water again, so can Spirit originate again out of matter, can proceed from matter, or, reversed, matter can again dissolve into Spirit.
Source: Rudolf Steiner – GA 55 – Origin of Suffering, Origin of Evil, Illness and Death: THE ORIGIN OF SUFFERING – Berlin, 8th November, 1906
Translated by M. Cotterell and V. E. Watkin